In rotary regenerative heat exchange apparatus a mass of heat absorbent element commonly comprised of packed element plates is first positioned in a hot gas passageway to absorb heat from the hot gases passing therethrough. After the plates become heated by the hot gases they are moved, frequently by rotation, into a passageway for a cool air where the then hot plates transmit their heat to the cool air or other fluid passing therethrough.
The heat absorbent element is usually carried by a cylindrical rotor that rotates between hot and cool fluids, while a fixed housing including sector plates at opposite ends of the rotor is adapted to surround the rotor and maintain the hot and cool fluids in separate ducts. To prevent mingling of the two fluids, the end edges of the rotor are usually provided with flexible sealing members that are intended to rub against the adjacent surface of the rotor housing to resiliently accommodate a limited degree of "turndown" or other distortion caused by thermal deformation and mechanical loading of the heat exchanger as brought about by temperature variation and normal bending stress caused by the force of gravity.
Originally the rotor and surrounding housing structure were relatively small and were accordingly supported solely by ductwork that directed the fluids to and from the heat exchanger. As the size of this type of apparatus was increased, the rotor was mounted on a bearing which was in turn carried by a horizontal support beam, either above or below the rotor. The housing was later supported directly or indirectly from the same beam whereby thermal and mechanically induced distortion of the beam would induce relative movement of the rotor and surrounding housing structure to allow leakage of fluid therebetween. Then, as the size of the apparatus was increased further, the weight of the rotor and surrounding housing structure was also increased so that a heavier support beam was required to preclude still more distortion; but, for large units as currently being provided, a heavy horizontal support beam and massive connecting plate structure is deemed essential to support the rotor and its surrounding housing.
Sealing means between the rotor and surrounding housing structure have been improved greatly to close the leakage paths therebetween, but in heat exchange apparatus of the rotary regenerative type there still exists excessive leakage that lowers the operating efficiency of the apparatus. Moreover, any reinforcement or stiffeners added to the rotor and rotor housing to preclude distortion necessarily add to the size and weight of the heat exchanger thus tending to produce still more distortion in the manner above cited. This produces still more fluid leakage, a lower efficiency, and increased operating costs.
Description of the Prior Art. Patents have been granted for rotary regenerative heat exchange apparatus having various arrangements that support a rotor and its surrounding housing structure so there will be a minimum amount of relative deflection therebetween.
U.S. Pat. No. 2,224,787 of Horney, U.S. Pat. No. 3,155,152 of Conde, and U.S. Pat. No. 3,874,442 of Johnsson are examples of apparatus wherein a central support beam is mounted at the top of the rotor to support both the rotor and the rotor housing. In U.S. Pat. No. 2,352,717 of Karlsson and U.S. Pat. No. 3,802,489 of Kirchoff et al, the rotor housing is supported at the bottom, the rotor in turn being supported by the housing structure.
In various other patents such as U.S. Pat. No. 3,016,231 of Muller, the exact support mechanism is not germane to the invention so it is not further disclosed. However, it should be assumed that in the absence of a valid teaching, all apparatus is supported by conventional support means.
For most applications it may also be assumed that the apparatus disclosed is for average sized units of less than 100,000 to 200,000 pounds. However, a heat exchanger according to this invention by comparison may have an overall weight of from one to two million pounds, of which the rotor may comprise three-fourths of the total weight while the rotor housing and support therefor will comprise the remaining portion of the total weight. It is thus apparent that when transmitted to a transverse support beam, these forces would effect a severe bending that when considered with the deflection caused by thermal distortion and weight of the beam itself would create an amount of relative movement between the rotor and surrounding housing that would be difficult, if not impossible, to properly contain or control. Therefore, fluid leakage from the apparatus would remain untenable.